House Oversight Committee Chairman Darrell Issa demanded Wednesday that the Federal Election Commission turn over records of more than five years of communications with the Internal Revenue Service -- a move that significantly expands the California Republican's ongoing probe of alleged federal targeting of conservative groups.

In a letter to FEC Chairman Ellen Weintraub -- a Democrat -- Issa cited CNN reporting on Monday that raises "the prospect of inappropriate coordination between the IRS and the FEC about tax-exempt entities."

Among other things, Issa asked for records of all communications between the IRS and the FEC dating back to the start of 2008. He also requested records of any FEC discussions relating to tax-exempt applications or organizations since 2008.

The letter was co-signed by Ohio GOP Rep. Jim Jordan, a prominent member of Issa's panel.

Iss'a letter came after Don McGahn, the vice chairman of the FEC and a Republican, told CNN that he saw an e-mail from an FEC investigator to Lois Lerner, the former head of the IRS division responsible for reviewing applications from various groups for tax-exempt status.

The investigator asked Lerner, herself a former FEC employee, to discuss the status of the American Future Fund, a conservative political advocacy group.

McGahn noted that after Lerner was contacted, the IRS sent a questionnaire to the American Future Fund.

Lerner, the figure at the center of the congressional investigation into alleged IRS targeting of conservative groups seeking tax-exempt status, invoked her Fifth Amendment right against self-incrimination when called to testify before Issa's panel in May.

"Dealing with Lois Lerner is probably out of the ordinary," McGahn said, stressing that FEC commissioners had not given their staffers permission to reach out to the IRS on the matter, a step typically required for such inquiries.

Last week, GOP congressional investigators disclosed several e-mails between Lerner and an FEC attorney inquiring about the status of both the American Future Fund and another conservative outfit, the American Issues Project.

Issa's letter identifies the FEC attorney as William Powers, an official in the commission's Office of the General Counsel.

The e-mails between Powers and Lerner were initially uncovered by House Ways and Means Committee Chairman Dave Camp, R-Michigan, who sent a letter last week to acting IRS Commissioner Daniel Werfel requesting additional details about the controversial contact.

While the prospect of potential FEC involvement with the IRS raises the prospect of a broader federal targeting effort, Democrats continue to insist there is no conspiracy, and stress that the publicly released contact between the two agencies was nothing more than requests for information already in the public domain.

McGahn told CNN, however, that additional e-mails he has seen do not clearly state whether the FEC was only seeking public data. Requesting private data would likely violate federal law.

For her part, Weintraub told CNN Monday she does not know about the e-mails between the FEC investigator and Lerner to which McGahn is referring.

"If there was any evidence or targeting based on ideology, that would be extremely serious, but I have not seen any evidence of that," she said.

"I am not aware of requesting or receiving any confidential taxpayer information. I am not aware of any requests for anything that wasn't publicly available."